Classical Cepheids are useful tracers of the Galactic young stellar population because their distances and ages can be determined from their period-luminosity and period-age relations. In addition, the radial velocities and chemical abundance of the Cepheids can be derived from spectroscopic observations, providing further insights into the structure and evolution of the Galaxy. Here, we report the radial velocities of classical Cepheids near the Galactic Center, three of which were reported in 2011, the other reported for the first time. The velocities of these Cepheids suggest that the stars orbit within the Nuclear Stellar Disk, a group of stars and interstellar matter occupying a region of ∼ 200 pc around the Center, although the three-dimensional velocities cannot be determined until the proper motions are known. According to our simulation, these four Cepheids formed within the Nuclear Stellar Disk like younger stars and stellar clusters therein.

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We present a comprehensive survey of diffuse interstellar bands (DIBs) in 0.91 − 1.32µm with the newly developed near-infrared (NIR) spectrograph WINERED, mounted on the Araki 1.3 m Telescope in Japan. We obtained high-resolution (R = 28, 300) spectra of 25 early-type stars with color excesses of 0.07 < E(B − V ) < 3.4. In addition to the five DIBs previously detected in this wavelength range, we identified 15 new DIBs, 7 of which were reported as DIB "candidates" by Cox. We analyze the correlations among NIR DIBs, strong optical DIBs, and the reddening of the stars. Consequently, we found that all NIR DIBs show weaker correlations with the reddening rather than the optical DIBs, suggesting that the equivalent widths of NIR DIBs depend on some physical conditions of the interstellar clouds, such as UV flux. Three NIR DIBs, λλ10780, 10792, and 11797, are found to be classifiable as a "family," in which the DIBs are well correlated with each other, suggesting that the carriers of these DIBs are connected with some chemical reactions and/or have similar physical properties such as ionization potential. We also found that three strongest NIR DIBs λλ10780, 11797, and 13175 are well correlated with the optical DIB λ5780.5, whose carrier is proposed to be a cation molecule with high ionization potential, indicating that the carriers of the NIR DIBs could be cation molecules.